As the guys stated it's a typical sign of a failing valve cover gasket. It's not a terrible hard diy, HERE is a link to one of the more detailed diys for you to read over. You'll need to pay attention to the build date on your car for which valve cover gasket set you need as there is a vin split in 09/2002.

The vanos gasket (BMW part number 11361433817) isn't terribly hard to change out. Depending on if you want to go ahead and do an anti rattle kit, change all the seals, etc it can get pretty involved. HERE is a link to a great diy and parts list for the E46 double vanos.